A light emitting diode (LED) is a kind of semiconductor light emitting device that converts electricity to light. The LED is also called a luminescent diode. The LED presents many advantages over conventional light sources, including smaller size, longer lifetime, low power consumption and high-speed responsiveness. Thus, the LED has been widely utilized in various applications such as a display device for an automotive instrument, a display lamp for various electronic devices such as an optical communication light source, a card reader for a numeric display device or a calculator, a backlight, and so forth.
The LED is manufactured through an EPI process, a chip process (fabrication) and a packaging process. The LED is subjected to a testing process after it is packaged through the packaging process. In the testing process, LEDs that do not operate normally (hereinafter, referred to as “inferior goods”) are excluded, and LEDs that operate normally (hereinafter, referred to as “fine goods”) are sorted into multiple classes depending on their performance and are then subjected to shipment.
Here, in the testing process, LEDs may be excluded as inferior goods or sorted into a lower class due to a problem caused during the packaging process, and they may be excluded as the inferior goods or sorted into the lower class due to a problem generated during the fabrication process in which they are fabricated in chip states (hereinafter, referred to as “LED chips”) before undergone through the packaging process.
That is, even in case no problem that affects the performance of LEDs is generated in the packaging process, the LEDs can be found to be inferior goods or sorted into lower classes due to the problems that are generated while the LED chips are fabricated.
The LEDs that are excluded as the inferior goods in the testing process due to the problems caused when the LED chips are fabricated are undergone through the packaging process and the testing process unnecessarily. As they undergo through the unnecessary processes, loss in material costs and process costs may be caused.
For LEDs that are sorted into lower classes due to the problems caused during the LED chips are fabricated, the reason that they are sorted into the lower classes may be sought for in the packing process. As a result, it has been time-consuming and cost ineffective in obtaining accurate analysis results.
The above-mentioned problems may result in an increase of a unit cost for the manufacture of products using LEDs as well as an increase of a unit cost for the manufacture of LEDs.